Transmission Control Protocol (TCP) is an underlying connection protocol that is typically used for all types of network communication. Different network routers set up connections with their peer routers using Border Gateway Protocol (BGP) over TCP to get route information from their peer routers allowing them to construct essentially an internal map of the network and to select the route that they should use, as well as verification that their peers are operating correctly. This is accomplished by sending various keep-alive and route update packets back and forth to make sure that their peers are still correctly functioning.
Peer routers view a conventional host router to which they are connected as a single logical entity represented essentially by the Master Control Processor (MCP). The MCP constructs route maps by establishing BGP adjacencies with peer routers using Dynamic Routing Protocol (DRP). Peer routers therefore infer that, if the MCP goes down or if their connection with it is terminated, the entire host router must have failed, and they will route around it. Conventional routers sometimes have dual redundant MCPs, but when the active MCP fails, the backup MCP essentially reboots and starts a new copy of the DRP software, which must then reestablish connections with all peer network routers. This switch-over event is visible to those peer routers, because they had established connections with the active MCP, the BGP protocol had established adjacencies with the conventional host router's BGP protocol, so they had an active link with the active MCP about which they had negotiated various parameters and routes they wanted to use. When the active MCP went down for whatever reason, those TCP connections were terminated and peer routers at the other ends of the connections knew that. They saw the connection as being closed, because a certain period of time after a link terminates, if the peer router at the other end tries to send traffic and receives no acknowledgments back, it infers that it has either lost a network path to the other end point of the link or that the other party has failed. Similar to talking through a telephone system, if there is a click and then silence, one party assumes they have lost the connection with the other party. Accordingly, if an active MCP were to fail, even if the backup MCP came on line in a conventional host router and started the routing protocol all over again, it basically would have to establish new connections. In the telephone analogy, if the phone hangs up during a conversation, one party must call the other party back.
Desired in the art are a system and method for network connection protocol, which maintains connections transparently between routers in the event of failure of an active MCP, such that a new set of connections between host router and peer routers does not have to be reestablished.